The present invention relates to a technology for mounting an electric component such as a semiconductor chip on a wiring board. More particularly, the present invention relates to a technology for mounting an electric component by using an adhesive.
In order to directly mount a bare chip on a wiring board such as a printed wiring board, a method is conventionally known which uses an anisotropic conductive adhesive film in which conductive particles are dispersed in a binder.
In the mounting method using the anisotropic conductive adhesive film, an IC chip is placed on a substrate with the anisotropic conductive adhesive film bonded thereto, and then the IC chip is pressed and heated with a flat bonding head formed of ceramic, metal, or the like, so as to cure the anisotropic conductive adhesive film. In this manner, mounting by thermocompression bonding is performed.
In the method using the bonding head formed of metal or the like for pressurization and heating, there is a problem that a heat applied to a fillet portion of the adhesive around the IC chip is insufficient during thermocompression bonding, thus lowering connection reliability. Moreover, there is also a problem that it is difficult to mount a plurality of IC chips.
Therefore, a technique has been proposed in recent years in order to overcome the above problems, in which thermocompression bonding of an IC chip is performed by using a thermocompression bonding head formed of an elastic material such as silicon rubber.
See, Japanese Patent Laid-Open Publication No. 2000-79611; and Japanese Patent Laid-Open Publication No. 2002-359264.
However, in the aforementioned conventional technique, a pressing force applied between a bump and a pattern which connect the IC chip and the substrate to each other is not sufficient. Thus, sufficient connection is not performed and it is not possible to ensure initial conduction resistance and connection reliability after aging.